Explosive actuated fastener driving tools



Dec. 3l, 1963 B. J. ELLIOTT ExPLosIvE ACTUATED FASTENER DRIVING TooLs Filed Aug. 11, 1961v INVENTOR ATTORNEY United States Patent Oliice llb? Patented Dec. 31, 1953 3,115,637 EXPLSIWE ACTUATEBD FASTENER DlrlJlNG TLS Bernard .lesse Elliott, Clifton Hill, Victoria, Australia,

.assigner to @lin Mathieson Chemical Corporation, a

corporation of Virginia Filed Ang. 11, 1961, Ser. No. 130,939 Il Claims. (Cl. 1-445) This invention relates to explosive actuated tools for driving studs or other fastener elements into walls or other solid surfaces, and more particularly it refers to tools of the kind in which the driving force of the explosive is transmitted to the fastener element through the intermediary of a piston-like member slidable in the barrel of the tool.

Tools of this type are known having a striker member slidably fitted through a breech piece removably fitted into the upper end of the barrel. The lower end of the striker member carries the explosive cartridge while the upper end proiects beyond the breech piece and is adapted to be struck a blow by a hammer or the like to drive the striker member into contact with the piston-like member and explode the cartridge.

With such tools, there is a risk of the cartridge being accidentally exploded during replacement of the breech piece in the barrel during loading of the tool, and the present invention has for its object to eliminate, or reduce to a great extent, this present risk of premature explosion.

With tools of this kind, it is desirable to` provide means for arresting the piston-like member in the event of over penetration of the fastener into the wall or surface due to use of an excessive explosive charge or the tool being used on a wall or surface not sufficiently resistant to hold the fastener. Usually, an arresting washer is used for the purpose, the kinetic energy of the piston-like member being absorbed by deformation of the washer. Such arresting washers, although efficient, have the disadvantage that they require to be replaced after deformation, an operation that can often canse inconvenience.

The invention consists of a breech piece for a fastener riving tool of the above-mentioned type characterized by having a shroud or skirt into which the cartridge-supporting end of the striker member is withdrawn for protection after insertion of the cartridge and before replacement of the breech piece in the barrel.

T here is also provided in a fastener driving tool of the type mentioned, means for arresting the piston-like member comprising an annular resilient or elastic member and means on the piston-like member whereby it is caused to be yieldingly arrested in the event of over travel by compression of the resilient or elastic member. Preferably a contact member is provided adiacent to the resilient or elastic member and the piston-like member strikes and applies its force to said contact member which, in turn, transmits it to the resilient or elastic member to compress the latter.

The invention is more fully described aided by reference to the accompanying drawings wherein:

FIG. l is a longitudinal sectional view of one type of fastener driving tool having a breech piece constructed according to the present invention.

PEG. 2 is a similar View of the upper end of the tool but showing the cartridge-supporting end of the striker member withdrawn into the depending shroud or skirt.

PEG. 3 is a similar View of the lower end of the tool showing the arresting means functioning.

As is shown in these views, the tool comprises a substantially cylindrical barrel 1 within the bore of which are slidably arranged the striker member 2 and the pistonlike member. At the upper end, the barrel supports a breech piece Li through which the shank 5 of the striker member slidably passes. The breech piece is releasable from the upper end of the barrel by any suitable means such as, for example, by a bayonet `type of connection or by a fast screw.

The breech piece encloses a cage 6 housing springpressed balls 7 which function to grip the shank 5 of the striker member to prevent accidental or premature firing. The balls '7 are released by means of release balls' 8 engaging the lower edge of the cage and actuated by a sleeve 9. Such construction, as described, is known and does not form part of the present invention.

According to the invention, a shroud or skirt 10 is provided on the breech piece 4. Said shroud or skirt is preferably of annular form and constructed as an integral depending extension on the lower end of the breech piece as shown. lt is spaced sufciently from the shank 5 to enable the lower cartridge-receiving end 11 of the striker member 2 to be Withdrawn into it. If said cartridge-receiving end 11 is of greater diameter than the shank 5 as is usual, the shroud or skirt is spaced from the shank 5 by the space 12. The shroud or skirt may be of any suitable thickness and may be completely closed or may be gapped as desired.

ln use, after the explosive cartridge has been inserted into the lower cartridge-receiving end 11 of the striker member, the striker member is retracted through the breech piece so that said lower end of the striker member with the cartridge is withdrawn into and enclosed by the shroud or skirt 10 as shown in FlG. 2. With the parts in this position, the breech piece 4 is then replaced in the barrel. The shroud or skirt adequately protects the cartridge during this operation and thus reduces risk of premature explosion and accident either through accidental dropping of the breech piece with the loaded striker member or through contact with any solid object.

The invention will be found particularly effective in tools where rim lire cartridges are used and the cartridge 30 is supported transversely of the longitudinal axis 0f the striker member 2 in an open-sided chamber in end 11 and with its primed rim exposed for firing when the striker member is driven downwardly against one or more firing projections 31 on the upper end of the piston-like member 3.

The improved arresting means for the piston-like member 3 comprise a resilient or elastic member 110 of rubber or elastomer of approved elasticity annular in form and seated against a base member 111 secured to the end of the barrel as by screws 112,. Above or adjacent to said 'annular resilient or elastic member, there is a metal retaining washer 113 and above and adjacent to said retaining washer there is a contact member 114 against which the piston-like member 3 strikes during the arresting action. The piston-like member E5 has an upper normal diameter portion 15 which slides within the bore of the barrel 1 and a lower reduced diameter portion 16 to pass freely through the contact member 114i, the washer 113, the resilient or elastic member 111i and the base member 111. The fastener element as 17 has its head seated in a recess 18 in the end of the pistonlike member and may be supported at its other end by a washer 19.

Between the normal diameter portion 15 and the reduced diameter portion 16 of the pistondike member 3 there is a tapered portion 2li. The bore of the contact member 111i is similarly tapered as at 21 and the two taper surfaces are complementary so that engagement is effected over a relatively large surface area. This ensures uniform distribution of the striking force over substantially the whole tapered surface 21 of the contact member.

The Contact member 11d may be seated against a shoul- 3 der 22 at the lower end of the barrel l and the whole arrester assembly held in position by the attachment of the base member lili by the screws 112.

Normally, the fastener element 17 in its penetration of the wail arrests the piston-like member 3 before its tapered portion 2d engages the Contact member 1M. If, however, through carelessness of error, an excessive explosive charge be used or the tool be used on a Wall or surface not sufficiently solid to hold the fastener element, the piston-like member 3 over travels until its tapered portion 2@ strikes the contact member Het and the impact is yieldingly or elastically borne by the annular resilient member lili?, the force being transmitted thereto from the contact member 114 through the washer 113. Thus, the piston-like member is yieldingly arrested and, as the annular resilient or elastic member, after compression, returns to normal position, the arresting means is eifective over long periods without replacement as is the case with the deformable washer arresting means above mentioned.

The complementary taper surfaces 20 and 21 prevent surface damage to the piston-like member, even under heavy impact as may occur should an excessive explosive charge be used or the tool is, through carelessness or error, used on a wall or surface not sufficiently thick or strong.

What is claimed is:

l. In a fastener driving tool of the type having a 'oarrel with a breech opening and a muzzle opening, the combination of a fastener-driving piston member adapted to receive a work surface impacting fastener in said muzzle opening, a striker member insertable in said barrel at said breech opening, said members being movable in said barrel relative to each other, said striker member having one end adapt-ed to be struck by a hammer and a cartridgesupporting end formed with an open-sided chamber for holding a rim iire type of explosive cartridge for disposition between said members and adapted for ignition by said members being moved together when said one end is struck While said fastener is impacted against said surface, and a breech piece detachably mounted in said breech opening for disassembly and reassembly with said barrel and movably carrying said striker member, said breech piece having a shroud recessed for receiving said cartridge-supporting end upon Withdrawal of said striker member.

2, The tool combination of claim l wherein the striker member has a shank reduced compared to the cartridgesupporting end, and wherein the shroud is a skirt which extends forwardly and outwardly in spaced relation from the shank to form in said breech piece a recess receiving said end and the received cartridge upon withdrawal of said striker member.

3. In a fastener driving tool of the type having a barrel with a breech opening and a muzzle opening, the combination of a fastener-driving piston member adapted to receive a work surface impacting fastener in said barrel at said muzzle opening, a striker member insertable in said barrel at said breech opening, said members being slideably movable in said barrel relative to each other and said barrel, chamber means in said striker member for receiving an explosive charge with part of the charge projecting between said members said striker member having one end adapted to be struck a hammer blow while said fastener is impacted against said surface, whereupon the members are percussively moved together against said charge to fire it and drive said piston member and sid fastener forwardly, and means for arresting an excessively overdriven piston member comprising:

(a) a side portion of said piston member having a taper,

(b) an oriiiced base abutment attached to said barrel at said muzzle opening,

(c) an annular resilient member seated against said base abutment,

(d) an annular contact member disposed movably in said barrel between said piston and resilient member and having a complementary taper for abutment with said` piston taper in the event of overdrive, whereby said piston is arrested by impact at said tapers and compression of said resilient member between said base abutment and moved contact member.

4. In a fastener driving tool of the type having a barrel with a breech opening and a muzzle opening, a fastenerdriving piston member having a portion slideably carried in the barrel adjacent the muzzle opening and an elongated piston front end portion of reduced diameter, and a striker member insertable in said breech opening to be slideably carried in said barrel, said piston member being movable by said striker member with relative movement including forcible projection of both said members toward said muzzle opening when the striker member is struck a blow, said striker member having a cartridge-supporting end formed with an open-sided chamber for holding a rim type of explosive cartridge in the barrel between said members with a rim of the cartridge exposed at one open side of the chamber for ignition by said blow, the improvement comprising a breech piece detachably mounted at said breech opening, movably carrying said striker member for disassembly and reassembly with said barrel and having a shroud defining a recess into which the cartridge-supporting end of the striker member may be withdrawn, and means for arresting said piston member comprising an oriced base abutment fixed on said barrel at the muzzle opening and formed with a bore aligned with said barrel for slideably engaging said elongated piston end portion, an annular resilient member having an exterior diameter contiguous with said barrel and an internal diameter larger than said elongated end portion of the piston member for receiving said piston end portion with clearance, an annular contact member mounted for movement adjacent said resilient member opposite said base abutment, and forwardly converging complementary tapers both on said contact member and on the piston between said piston end portion and said slideable portion, whereby the piston member is arrested in the event of overtravel by contact of said tapers and compression of said resilient annular member between said base abutment and said contact member.

Temple Nov. 12, 1940 Maier Aug. 5, 1958 

1. IN A FASTENER DRIVING TOOL OF THE TYPE HAVING A BARREL WITH A BREECH OPENING AND A MUZZLE OPENING, THE COMBINATION OF A FASTENER-DRIVING PISTON MEMBER ADAPTED TO RECEIVE A WORK SURFACE IMPACTING FASTENER IN SAID MUZZLE OPENING, A STRIKER MEMBER INSERTABLE IN SAID BARREL AT SAID BREECH OPENING, SAID MEMBERS BEING MOVABLE IN SAID BARREL RELATIVE TO EACH OTHER, SAID STRIKER MEMBER HAVING ONE END ADAPTED TO BE STRUCK BY A HAMMER AND A CARTRIDGESUPPORTING END FORMED WITH AN OPEN-SIDED CHAMBER FOR HOLDING A RIM FIRE TYPE OF EXPLOSIVE CARTRIDGE FOR DISPOSITION BETWEEN SAID MEMBERS AND ADAPTED FOR IGNITION BY SAID MEMBERS BEING MOVED TOGETHER WHEN SAID ONE END IS STRUCK WHILE SAID FASTENER IS IMPACTED AGAINST SAID SURFACE, AND A BREECH PIECE DETACHABLY MOUNTED IN SAID BREECH OPENING FOR DISASSEMBLY AND REASSEMBLY WITH SAID BARREL AND MOVABLY CARRYING SAID STRIKER MEMBER, SAID BREECH PIECE HAVING A SHROUD RECESSED FOR RECEIVING SAID CARTRIDGE-SUPPORTING END UPON WITHDRAWAL OF SAID STRIKER MEMBER. 